NATIONAL DATABASE OF METAL IN COMPARATIVE PERSPECTIVES OF THE UNITED KINGDOM & INDONESIA

The ocean is a source of mega-biodiversity that is supposed to perform optimally for current and future generations. The health of the ocean must be evaluated by measuring heavy metals in sediment because they can be accumulated and stored in long term. This metal can be released and absorbed by an organism, and affect the ecological risk and human health. The purpose of this article is to share viewpoints and those in a comparative study in terms of the metal database of both countries, the UK and Indonesia. The methodology used in this paper is critical review and analysis to compare a success story about compiling metal data into a national database in the United Kingdom (UK). Indonesia already has an open public access database issued by the Ministry of Environment and Forestry. The further step is to strengthen collaboration between research institutes, universities, and government to assign a Standard Operational Procedure (SOP) to collect, analyze and report the data to a national depository. This database will be worthwhile to describe the pollution status in Indonesia and basic data for best practice decisions.

Identification of suspected paleotsunami deposits study from Karapyak Beach, Pangandaran area, West Jawa, Indonesia

Identifying and constraining palaeotsunami deposits can be a vital tool for establishing the periodicity of earthquakes and their associated tsunami events beyond the historical records. However, the deposits can be difficult to establish and date. In this study we used the characteristics of the 2006 Pangandaran tsunami deposit as a reference for identification of paleotsunami deposits in Karapyak Beach, Pangandaran area, West Java, Indonesia. Similar to the 2006 Pangandaran tsunami deposit, the Karapyak Beach paleotsunami deposit is characterized by light brown loose sand materials overlying a dark brown paleosoil layer with erosional contact. A thin layer that varies in thickness is locally found right above the erosional contact, with non-laminated coarser grain in the lower part that gradually change into medium to fine sand-sized in upper part. The base of the lower part is rich with broken mollusc shells and corals, and the mid-top of the lower part may contain several intact molusc shells and corals, rock fragments and anthropogenic products (rooftile). Those types of fragments are absent in the upper part of the thin layer. Grain size analysis shows a mixture of fine and coarse grains in the lower part of 2006 tsunami deposits as well as in the suspected paleotsunami deposits, suggesting uprush high energy flow during sedimentation. Fining upward sequence above mixed grain layers reflects waning flow or pre-backwash deposition. Foraminifera analysis also shows a mixture of shallow and deep marine foraminifera in the two deposits. Based on the characteristics of the 2006 tsunami deposits, there are at least four identified paleotsunami deposits at Karapyak Beach, Pangandaran area.

A SUCCESS CASE OF WIDURI AREA REJUVENATION, ASRI BASIN, OFFSHORE SE SUMATRA BLOCK, INDONESIA

INTA/B Field is one of the most producing mature fields in Widuri Area, Asri Basin, Offshore SE Sumatera, Indonesia, therefore it is subjected to rejuvenation to enhance hydrocarbon production. INTA/B Field is distinguished from other fields from its featured anticlinal structures that have the northeast-southwest trending. This structure is heavily faulted mainly in the up-thrown south side of a major normal fault. Two structural configurations with various oil-water contact have successfully been identified within the field. The most of oil reserves are preserved in the western lobe in which Intan-1 sands. One of the most important reservoirs in this field is Talangakar (TAF) sand deposited as a meandering river system that streamed from the northwest to the southeast within the basin. Two main reservoirs, Gita-34A and Gita-34B are correlated throughout the field and interpreted as Miocene fluvio-channel sands. These two channels are thickened moderately from southwest to northeast which has descriptions as follows: fine- to-coarse grains, unconsolidated to friable, and low cementing materials.INTA/B Field has been produced for 25 years and currently undergoing a watered-out phase. Therefore, an integrated study is subjected to overcome this issue for mature field rejuvenation. The integrated study ranged from geology (e.g., depositional environment and facies analysis), geophysics (e.g., revisiting and reprocessing of seismic attributes), petrophysical calculation, and reservoir engineering (e.g., water conformance plot and volumetric calculation).This integrated study has successfully rejuvenated a mature field resulting and added a significant number in oil production with an average of 300 BPOD/well. The extended project is estimated to have a similar result to the forward pilot.

PETROPHYSICAL ANALYSIS AND SEISMIC STRATIGRAPHY INTERPRETATION TO DETERMINE HYDROCARBON RESERVOIR IN TARAKAN BASIN, BUNYU ISLAND WATERS

Tarakan Basin area of Bunyu Island Waters is known to have hydrocarbon potential with complex geological structures. This study aims to determine reservoir characterization and to obtain prospect of hydrocarbon reservoir zones based on petrophysical and seismic stratigraphy analysis with reference to Well DDS-1 and 2D seismic Line S88. Petrophysical analysis results 3 zones that have potential as hydrocarbon reservoirs. Based on petrophysical quantitative analysis, Zone 1 has values of 52.25% for shale volume, 18.48% for effective porosity, 39.84% for water saturation and 13.03 mD for permeability. Zone 2 has values of 54.66% for shale volume, 10.27% for effective porosity, 40.9% for water saturation and 1.14 mD for permeability. Zone 3 has values of 49.22% for shale volume, 9.33% for effective porosity, 56.33% for water saturation and 0.22 mD for permeability. Out of these three reservoir zones in Well DDS- 1, Zone 1 has the prospect of hydrocarbons which is supported by the net pay value. Based on seismic stratigraphy interpretation, the reservoir zone is correlated to the Tabul Formation, which comprises calcareous clay and limestone.

ASSESSMENT OF POTENTIAL MARINE CURRENT ENERGY IN THE STRAITS OF THE LESSER SUNDA ISLANDS

The Lesser Sunda Islands extend from Bali to Timor and consist of two geologically distinct parts formed by a subduction system of oceanic crust along the Java-Timor Trench. The northern part which includes Bali, Lombok, Sumbawa, Flores, Wetar, Pantar and Alor, is volcanic in origin; whilst the southern part is non-volcanic, encompassing the islands of Sumba, Timor and Rote. The straits along the Lesser Sunda Islands are formed as a result of very complex geological processes and tectonics in this area. These straits are the most important cross-sections in the southern part of the Indonesian Throughflow (ITF), functioning as outlets for the mass flows of seawater from the Pacific Ocean to the Indian Ocean through the Flores and the Savu Seas. In these straits, relatively high current speeds are occurred, not only caused by the ITF but also due to its geometry, the influence of tidal flow, and monsoonal currents.Site study and ocean current measurement were conducted by using an echosounder, a pair of Acoustic Doppler Current Profilers (ADCP), and other supporting equipment. In general, the average of most ocean current speeds is less than 1.5 m/s with a duration flow of 8 -12 hours a day, and the maximum speed reaches up to 3 m/s. The tidal types in almost all the straits are mixed semidiurnal tides, in which two high waters and two low waters occur twice a day, with the high and low tides differ in height.The Lesser Sunda Straits were selected as the potential sites for ocean current power plant because their current speeds are relatively high and their characteristics are more predictable compared with other straits from other regions. Based on the results of bathymetry survey and current characteristics from the deployed ADCP at a fixed (stationary) location on the seabed, the best location for the current power turbines is at the depth of 15-30 m where the seabed gently sloping.

DISTRIBUTION OF SUBSURFACE QUATERNARY SEDIMENT IN SOUTH BINTAN ISLAND WATERS AS A POTENTIAL HEAVY MINERAL PLACER OR RARE EARTH ELEMENT DEPOSIT BASED ON SEISMIC INTERPRETATION

Bintan Island is one of the areas traversed by the Southeast Asian granitoid belt which is known to have the potential for heavy mineral placer deposits. Due to the dwindling presence of heavy mineral placer deposits in land areas, it is necessary to look for the potential presence of heavy mineral placer deposits in water areas. Searching for placer heavy mineral deposits accomodation in these waters requires subsurface mapping.The method used in this subsurface mapping is a single channel seismic method with a total of 179 lines in the direction of northeast – southwest and west – east. The results of this seismic recording are then interpreted the boundaries of the seismic facies unit and distributed using the kriging method. Furthermore, the thickness calculates by using the assumption velocity 1600 m/s.Based on the facies unit boundaries that have been interpreted, the quaternary sediments that formed in the study area are divided into 2 types of units, namely: Unit 2 which is estimated to be fluvial – transitional sediment, and Unit 1 which is estimated to be transitional sediment – shallow sea. There is also a difference in thickness patterns in these two units, where unit 2 shows a pattern of sediment thickening that resembles a paleochannel trending northeast – southwest, while unit 1 is relatively uniform.From the results of this study, it can be said that the area that has potential for heavy mineral placer deposits is in the west - center of the southern waters of Bintan Island. Where the potential for heavy mineral placer deposits should be in the paleochannel deposits that are part of Unit 2.

QFL AND LITHO FACIES: PREDICTING RESERVOIR QUALITY OF THE MIDDLE MIOCENE DEEP-WATER FACIES AT KUTEI AND NORTH MAKASSAR BASINS

As we may all be aware the oil and gas wellbores offshore Kutei and North Makassar have not optimally penetrated the objective strata, which is the Middle Miocene’s deep-water reservoirs. Therefore, evaluating the quality of these reservoirs with onshore dataset then comparing them with the proven Late Miocene’s deep-water producing reservoirs had been very fundamental. The study focuses on the assessment of QFL and sandstones litho-facies based on the rock samples from conventional-core and side-wall core, and well-logs data from forty wells onshore and offshore. These rock samples are bounded by the key biostratigraphy intervals of M40M33, M45M40, M50M45 (Middle Miocene), and M65M50, M66M65, M70M66, M80M70 (Late Miocene). Subdivisions of the reservoirs considered the sandstone litho facies, NTG ratio, sorting, and grain size, to come up with five groups in the Middle Miocene deltaic facies: FLU_SX, DC_SX, DC_SM, DC_SM, and DF_SC; and four groups in the Late Miocene deep-water facies: SSWS, MSWS, SSPS, and MSPS. Core-based porosity and permeability further explain the relationship between the reservoir quality with the sandstones’ composition and litho facies, and concluded that high-energy depositional system is mainly associated with the FLU_SX, DC_SX, SSWS and MSWS being the reservoir with best quality. Oppositely, the DF_SC, SSPS, and MSPS are classified the reservoir with worst to none quality. A cross plot between core-based porosity and maximum burial depth is able to postulate the relational trend of decreasing reservoir quality with deeper depth.

Application of Spectral Decomposition and RGB Blending for Delineation of “S” Channel At Asri Basin

Gita member is part of Talang Akar Formation is known as hydrocarbon reservoir at Asri Basin, eastern part of South Sumatra. This formation consists of several depositional systems such as braided channel, meandering channel, fluvial-deltaic, and estuarine system. A channel system was an interesting system developed in the Asri Basin, however, to get the channel distribution in Asri Basin is quite challenging because the thickness of the channels caused its appearance is generally close or under seismic resolution, the existence of coal below our target also affects the impression of “S” sand on seismic data. In this study, spectral decomposition and RGB Blending have been successful to identify “S” sand. RGB Blending map is extracted from 15 Hz as low frequency, 45 Hz as middle frequency, and 75 Hz as high frequency. Our interpretation was applied at RGB Blending map and reveal the “S” sand is classified as a meandering channel depositional system with the main direction of the channel is Northeast – Southwest.

Estuary Changes of Cipunagara and Cimanuk River Using Landsat Imagery Spatial Analysis

The north coastal Java located in the West Java, especially in Cirebon, Indramayu, and Subang, occurs loss and forming new land by abrasion and accretion processes. Observation using satellite imagery can be used as an initial stage to determine the distribution of abrasion and accretion around the north coastal area. Observation of land changes was assigned using Landsat imagery from 1978 to 2020. The result shows that inland change was controlled by abrasion and accretion. It is occurred in Indramayu and Subang, especially in several areas around large rivers e.g. Cipunegara and Cimanuk Rivers. Estuary changes in the Cipunegara and Cimanuk Rivers were controlled by the high flux sediment deposition of the river mouths affecting the new land forming due to the accretion process. Monitoring through Landsat satellite imagery on the Cipunagara River from 1978 to 2020 shows that there was 205 Ha of new land. Remote sensing analysis in the Cimanuk River area shows that the estuary line from 1978 to 2020 experienced accretion or new land forming for 629 Ha.

Tectonics of Volcanogenic Massive Sulphide (VMS) Deposits at Flores Back Arc Basin: A Review

The bathymetry, petrology, marine magnetic, and seismic-SBP data have identified the northwest-southeast direction submarine ridge that shows hydrothermal activity. This activity occurred through Mount Baruna Komba, Abang Komba, and Ibu Komba. The volcanic rocks are andesite basaltic lava flows, tuff, and pumice. The andesite basaltic lava shows porphyritic, intergranular, intersertal to glomeroporphyritic textures. The rock composes anhedral minerals of k-feldspar, plagioclase, and pyroxene. These minerals present in small-sized, short prismatic dispersed in very fine groundmass minerals or glasses. Most of the volcanic rocks have experienced various degrees of alteration. The k-feldspar and plagioclase are most dominantly transformed into sericite, clay mineral, carbonate, epidote and oxide mineral, opaque mineral, and secondary plagioclase through the albitization process, while pyroxene replaced by chlorite. Other minerals are biotite and quartz, and base metals are present Cu, Zn, Ag, As, Pb, and gold. Mineralization categorizes as the phyllic zone, sub-prophylithic zone, and phyllic-potassic zone that formed at a temperature range of 250-400oC. The submarine hydrothermal alteration in the Komba Ridge is associated with a volcanogenic sulphide deposit controlled by crust thinning due to the crust rifts in the back-arc tectonic setting.